Method and dispensing device for dispensed fluid output

Abstract

A dispensing device which has a dispensing channel extending between a supply opening and an output opening into the course of which a pump, a selection valve and a dispensing valve are connected. The selection valve is also connected to a pressurised air source. The dispensing device allows a dispensed output of a fluid, wherein a buffer channel portion is filled by the pump in a pump dispensing phase, to which buffer channel portion pressure is applied from the pressurised air source during a pressurised air dispensing phase such that a precise fluid output is subsequently possible by clocked actuation of the dispensing valve until the target fluid amount has been reached.

What is claimed is: 
     
       1. A method for dispensed output of a fluid at an output opening of a dispensing channel of a dispensing device, the method comprising:
 (a) outputting a first proportion of a target fluid amount to be output by means of a pump connected into the dispensing channel which pump sucks the fluid to be dispensed via a supply opening of the dispensing channel from a fluid reservoir; 
 (b) applying pressurised air to a buffer channel portion of the dispensing channel upstream of the output opening, which buffer channel portion is separated both from the output opening and from the pump and is filled with fluid sucked by the pump such that the buffer channel portion including a fluid buffer volume confined therein is placed under pressure; and 
 (c) subsequently outputting, in a clocked manner, the remaining proportion of the target fluid amount to be dispensed from the buffer channel portion, which is separated from the pump and pressurised by the pressurised air, by means of a dispensing valve arranged between the buffer channel portion and the output opening in the dispensing channel, which dispensing valve is switched alternately into an open position allowing a fluid passage and into a closed position preventing a fluid passage, 
 wherein the method is carried out by means of a dispensing device which has a selection valve arranged in the course of the dispensing channel between the pump and the dispensing valve, which selection valve has a pressurised air inlet connected to a pressurised air source and is selectively switchable into a pump operating position or into a pressurised air operating position, said selection valve connecting a output channel portion of the dispensing channel extending between the selection valve and the output opening to the pump in the pump operating position and to the pressurised air inlet in the pressurised air operating position, the following method steps being carried out: 
 (a) operating the dispensing device in a pump dispensing phase in which the selection valve is held in the pump operating position when the pump is running and the dispensing valve is in the open position at the same time until the first proportion of the target fluid amount to be dispensed of the fluid sucked via the supply opening is output at the output opening; and 
 (b) subsequently operating the dispensing device in a pressurised air dispensing phase, wherein during a first sub-phase of the pressurised air dispensing phase by switching over the selection valve to the pressurised air operating position and by switching over the dispensing valve to the closed position the buffer channel portion of the dispensing channel which is filled with fluid by the pump during the pump dispensing phase being placed under pressure by feeding in pressurised air, and wherein during a second sub-phase of the pressurised air dispensing phase subsequent thereto the dispensing valve being switched over in a clocked manner between the open position and the closed position until the remaining proportion of the target fluid amount to be dispensed is output from the buffer channel portion at the output opening.